Cellular communications systems typically provide interconnect and/or dispatch voice communication services. Interconnect voice communication services are those typically provided by most cellular carriers as circuit-switched communications. Dispatch communication services are commonly known as a push-to-talk (PTT) or walkie-talkie type of call such as Sprint Nextel Corporation's service identified by the trade name Direct Connect. Interconnect voice communication services provided by most cellular carriers can be provided between sources and destinations of different cellular carriers. However, dispatch communication services are typically implemented using different protocols which prevents dispatch calls from originating in one cellular carrier's network and terminating in another cellular carrier's network.